Field of the Invention
The present invention relates to the field of the manufacture of electronic components, and more particularly to a pin and a printed circuit board.
Description of the Prior Art
A printed circuit board is widely applied to data switching exchange and telecom equipment. Electronic components of the printed circuit board are mostly mounted on the printed circuit board by a surface mounted technology. In view of economical efficiency and quality, automatic assembly of the mechanism parts on the printed circuit board needs to be realized. Ensuring the quality at the same time as realizing assembly automation is a problem faced in the design of the mechanism.
A pin is a most common and necessary component of the printed circuit board. When the pin is assembled by automatically picking and placing, it is necessary to form a gap between the pin and an insertion hole, thereby satisfying the requirement of manufacturing processes. But an oversized gap could result in a tilt of the pin and cause quality problems. Therefore, the gap between the pin and the insertion hole must be reduced as much as possible when designing the pin. In order to avoid the pin not being smoothly inserted into the insertion hole of the printed circuit board during assembly, the size of an insertion head of the pin must be smaller than that of the insertion hole of the printed circuit board. That is, the pin and the insertion hole should be in a clearance fit.
FIG. 1A is a structural schematic view of a pin in the prior art. The pin includes a pin body 10, an insertion head 11 and a welding head 12. The insertion head 11 is disposed on an end of the pin body 10, and the welding head 12 is disposed on an opposite end of the pin body 10 to the insertion head 11. The insertion head 11 is cylindrical.
FIG. 1B is a structural schematic view of another pin in the prior art. In FIG. 1B, the pin includes a pin body 10′, an insertion head 11′ located on an end of the pin body 10′, and a welding head 12′ located on an opposite end of the pin body 10′ to the insertion head 11′. The shape of the insertion head 11′ is a quadrangular prism.
In FIGS. 1A and 1B, the shapes of the insertion heads are single, which are cylindrical or a quadrangular prism. In the course of inserting the pin into the insertion hole of the printed circuit board, the cylinder has a greater risk of touching the edge of the insertion hole than the quadrangular prism, the circumcircle of which has the same diameter as that of the cylinder. However, the prism, the cross section of which is polygonal, can result in an oversized gap between the insertion head and the insertion hole. The oversized gap needs to be filled with more solder material to avoid a problem of poor welding.